This route going free was a wild vision from British climber Stevie Haston. After climbing it, I have to agree with his assessment in his article "Free Mud" in Alpinist Magazine and will add to it here. 

In a way, the first pitch of Sun Devil is one of the best pitches the desert has to offer. Roof climbing, sporty face moves between mono & two finger pinscars and little cobbles cemented in the mud, and gear that is just good enough to hold but far enough apart to make things interesting. The only part that is less desirable is the consistent layer of dirt on every hold but it really does add another level of challenge to the experience. I doubt there is climbing like this anywhere else in the world.

To add to that, the second pitch is a rad straight-in-splitter (both p1&2 are slightly overhanging) with thin hands and fingers moves between good hand jam rests. The exposure is incredible, partly due to the fact that the entire wall moans and you really don't want to trust the anchors, and partly because both p1 & 2 are both over 150 ft long - so you basically climb the height of the Rectory or Castleton in two pitches.

Once you are in the chimneys you get to navigate a crazy world of slopers, tufa-like-mud curtains, and wide, airy stemming. Its the kind of free climbing that is unforgettable.

Once you are out of the chimneys you get to do some sweet offwidth climbing with a wild view of the desert.

The physical crux is the first pitch. The mental crux is either the end of 3 or the cumulative experience of 4. 5,6,7 are tough but you will definitely take it to the top if you finish 4.

Same start as for the aid route. At the very start of pitch 4 the free route traverses into the chimney 20' earlier than the aid route.  On pitch 6, you follow the wide crack to the right where the aid route heads left. Other than that you follow the aid line. 

A specific trad rack will make the first two pitches secure. Bring a ballnut and tricams for the crux of pitch 3. Large hexes for the mud curtains on 4. At least 8 draws for clipping aid bolts and some wide gear #4-6 for pitch 5 and 6.